Like almost all of Saki's stories, "The Interlopers" has a darkly ironic ending. Just as Ulrich and Georg choose to end their feud and work together toward their mutual rescue, their teamwork results in summoning the wolves. Saki's ending implies that the men are killed by the wolves instead of being rescued by their men. The ending serves multiple purposes rather than simply being a stylistic choice on Saki's part. Below are several interpretations.
1. Even though the men appear to become friends, right before Ulrich sees that their "rescuers" are wolves, the two men continue to focus on whose men will rescue them. Georg keeps asking Ulrich if he can make out whose men are on their way, implying that he is still in competition with Ulrich. Thus, Saki demonstrates that Georg and Ulrich most likely would have gone back to their old feuding ways if they had been rescued by each other's men.
2. The men presumably die on the very land over which they had fought for decades. Saki, no doubt, chooses this setting for their deaths to illustrate the futility of fighting over possessions. In the end, neither man will be alive to lay claim to the land.
3. Finally, it is fitting that the author chooses "wolves" to kill the men. For as Ulrich and Georg lie trapped under the tree, agreeing to be friends, one has to wonder which--if not both--of them is the "wolf in sheep's clothing" who will turn on the other as soon as they are rescued.